Catalyst-coated ionomer membrane with protective film layer and membrane-electrode-assembly made thereof

ABSTRACT

The present invention relates to the field of electrochemical cells and fuel cells, and more specifically to polymer-electrolyte-membrane fuel cells (PEMFC) and direct methanol fuel cells (DMFC). It is directed to catalyst-coated ionomer membranes (“CCMs”) and membrane-electrode-assemblies (“MEAs”) that contain one or more protective film layers for protection, sealing and better handling purposes. The one or more protective film layers are attached to the surface of said catalyst-coated membranes in such a way that they overlap with a region of the passive non-coated ionomer area, and with a region of the active area that is coated with a catalyst layer. Furthermore, the present invention discloses a process for manufacture of CCMs and MEAs that contain protective film layers. The materials may be used as components for the manufacture of low temperature fuel cell stacks.

FIELD OF THE INVENTION

[0001] The present invention relates to the field of electrochemicalcells and fuel cells.

BACKGROUND

[0002] Fuel cells convert a fuel and an oxidizing agent intoelectricity, heat and water at two spatially separated electrodes.Typically in fuel cells, hydrogen or a hydrogen-rich gas is used as thefuel, and oxygen or air is used as the oxidizing agent.

[0003] The energy conversion process in fuel cells is distinguished byparticularly high efficiency. For this reason, fuel cells are gainingincreasing importance for mobile, stationary and portable applications.

[0004] The polymer electrolyte membrane fuel cell (PEMFC) and the directmethanol fuel cell (DMFC, a variation of the PEMFC, powered directly bymethanol instead of hydrogen) are two common types of fuel cells thatare used as energy converting devices. They are attractive choicesbecause typically, they have compact designs, desirable power densitiesand high efficiencies.

[0005] The technology of fuel cells is well known to persons skilled inthe art and is broadly described in the literature, see for example, K.Kordesch and G. Simader, “Fuel Cells and its Applications,” VCH VerlagChemie, Weinheim (Germany) 1996. Nonetheless, in order to aid in theunderstanding of the present invention, in the following section,certain technical terms and phrases that are used in the presentdisclosure are described in greater detail:

[0006] A “catalyst-coated membrane” (hereinafter abbreviated “CCM”)consists of a polymer electrolyte membrane that is provided on bothsides with a catalytically active layer. One of the layers takes theform of an anode for the oxidation of hydrogen and the other layer takesthe form of a cathode for the reduction of oxygen. Because the CCMconsists of three layers (anode catalyst layer, ionomer membrane andcathode catalyst layer), it is often referred to as a “three-layer MEA.”As outlined in this disclosure, a CCM may also contain one or more filmlayers for better protection, handling and sealing of the product.

[0007] “Gas diffusion layers” (“GDLs”), sometimes referred to as gasdiffusion substrates or backings, are placed onto the anode and cathodelayers of the CCM in order to bring the gaseous reaction media (e.g.,hydrogen and air) to the catalytically active layers and, at the sametime, to establish an electrical contact. GDLs usually consist ofcarbon-based substrates, such as carbon fiber paper or woven carbonfabric, which are highly porous and provide the reaction gases with goodaccess to the electrodes. Furthermore, they are hydrophobic and permitremoval of the product water from the fuel cell. Additionally, GDLs canbe coated with a microlayer in order to improve the contact to themembrane. They can also be tailored specifically into anode-type GDLs orcathode-type GDLs, depending on into which side they are built in agiven MEA. Furthermore, they can be coated with a catalyst layer andsubsequently laminated to the ionomer membrane. These types ofcatalyst-coated GDLs are frequently referred to as “catalyst-coatedbackings” (abbreviated “CCBs”) or gas diffusion electrodes (“GDEs”).

[0008] A “membrane-electrode-assembly” (“five-layer MEA”) is the centralcomponent in a polymer-electrolyte-membrane (PEM) fuel cell and consistsof five layers: the anode GDL; the anode catalyst layer; the ionomermembrane; the cathode catalyst layer; and the cathode GDL. A MEA can bemanufactured by combining a CCM with two GDLs (on the anode and thecathode side) or, alternatively, by combining an ionomer membrane withtwo catalyst-coated backings (CCBs) at the anode and the cathode sides.In both cases, a five-layer MEA product is obtained. When the CCMcontains one or more protective film layers integrated in the laminatedassembly, the five-layer MEA in turn contains the protective film layeror layers as well.

[0009] The anode and cathode catalyst layers are comprised ofelectrocatalysts that catalyze the respective reactions (e.g., oxidationof hydrogen at the anode and reduction of oxygen at the cathode).Preferably, the metals of the platinum group of the periodic table areused as the catalytically active components, and for the most part,supported catalysts are used in which the catalytically active platinumgroup metals have been fixed in nano-sized particle form to the surfaceof a conductive support material. By way of example, carbon blacks withparticle sizes of 10 to 100 nm and high electrical conductivity haveproven to be suitable as support materials. In these applications, theaverage particle size of the platinum group metal is typically betweenabout 1 and 10 nm.

[0010] The “polymer electrolyte membrane” consists of proton-conductingpolymer materials. These materials are also referred to below as ionomermembranes. In ionomer membranes, tetrafluoroethylene-fluorovinyl-ethercopolymer with sulfonic acid groups is preferably used. This material ismarketed, for example, by E.I. DuPont under the trade name Nafion®.However, other, especially fluorine-free, ionomer materials such assulfonated polyether ketones or aryl ketones or acid-dopedpolybenzimidazoles may also be used. Examples of materials that aresuitable as ionomer materials are described by O. Savadogo in “Journalof New Materials for Electro-chemical Systems” I, 47-66 (1998). Forapplication in fuel cells, these membranes generally have a thicknessbetween 10 and 200 μm.

[0011] Within fuels cells such and PEMFCs, one may stack severalmembrane-electrode-assemblies and bipolar plates in series to obtain thedesired voltage output. As persons skilled in the art are aware, in fuelcell stack technology, sealing of components is an important issue.Generally, it is necessary to achieve a gas-tight sealing of thesecomponents (predominantly CCMs, MEAs and bipolar plates) against leakageto the environment and against intermixing of the reactants (hydrogenand oxygen/air). This gas-tight seal is essential for the safety of aPEMFC stack. (Lack of safety is a serious obstacle for the widespreadintroduction of fuel cell technology.) Thus, the quality and enduranceof the seals and the materials used for them are of primary importance.

[0012] For different stack architectures and operating conditions (suchas pressure, temperature, fuel gases and lifetime required) differentsealing concepts and technologies must be applied and developed.Furthermore, an appropriate sealing concept for CCMs and MEAs shouldalso take into account an improvement for better protection and betterhandling of these products. Better handling and processing isparticularly important in view of a large scale continuous production ofCCMs and MEAs.

[0013] Various concepts and technologies for sealing of MEAs and CCMsare described in the prior art.

[0014] In U.S. Pat. No. 3,134,697, a sealing function is conventionallyachieved by using pre-cut frames of a polymer material and placing theseframes around the electrodes of the fuel cell between the membrane andthe bipolar plates of the cell. However, this concept suffers from thehigh efforts needed for exact handling and positioning of the cell,membrane-electrode-assembly and gasket frames. Thus, there is no closecontact between membrane and sealing.

[0015] EP 690 519 addresses the stabilization of the membrane in theinactive sealing region. It relates to an assembly consisting of atleast one seal layer in a solid polymer ion exchange layer, wherein theseal layer or layers cover essentially only the region of the ionexchange layer that is to be sealed. According to this application, thesealing layer is made of polytetrafluoroethylene (PTFE) film having onesurface coated and partially impregnated with the ionomer material.

[0016] A similar concept is pursued in WO 00/74160. This documentdescribes a membrane electrode unit for fuel cells. There the membraneelectrode unit comprises a reinforcing frame that is situated on theperiphery and in the area of openings that are placed in the activeportion of the membrane electrode unit and provided for guiding materialor for installation. A reinforcing frame is formed by a hot melt typeadhesive layer that is applied on both sides and is formed by at leastone rigid plate.

[0017] All of these concepts described in the aforementioned referencesare based on sealing frames or layers that cover the peripheral membranerim of the CCM/MEA and only stabilize this peripheral rim. However,depending on fuel cell operating parameters, frequently failures in themembrane material may occur at the interface between the active area andthe sealing layers. Therefore, sufficient overlap is needed between thesealing/gasket layer, the active electrode layer and the ionomermembrane.

[0018] WO 00/74161 relates to a membrane-electrode-assembly provided forfuel cells or the like that comprises an ionomer membrane that is coatedon both sides with electrodes. The sealing edge, which is configured onthe outer periphery, is comprised of a hot melt adhesive whosehydrocarbon skeleton carries, at regular intervals, ionic or strongpolar groups that enter into a surface interaction with the ionic groupsof the membrane material and thus provides for good adhesive effect ofthe hot melt type adhesive to the polymer electrolyte membrane. Thethermoplastic sealing made of hot melt type adhesive extends on bothsides over the edge section of the membrane. Unfortunately, associatedwith this method are high production costs, as well as costs for theapplication form of the hot-melt adhesive. Furthermore, its long-termstability is not proven; various components (such as hardeners,defoamers and other additives) may be leached out during operation andmay cause deterioration of the MEA.

[0019] WO 00/10216 describes a membrane electrode gasket assembly(“MEGA”) having a gasket and a sub-gasket to seal the MEA and to protectit from possible edge failures. The gasket material typically consistsof expanded polytetrafluoroethylene (e-PTFE), soaked with a solution ofionomer for better adhesion. The sub-gasket is disposed over aperipheral portion of an electrode, which is applied to a centralportion of an ionomer membrane. In the examples given in WO 00/10216, asimultaneous overlapping of the sub-gasket with the electrode portionand the non-coated ionomer membrane portion is not disclosed.

[0020] A different concept is suggested in U.S. Pat. No. 5,176,966.According to that patent, seals are formed by impregnating the layers ofporous electroconductive sheet material of the membrane electrodeassembly with a sealant material that generally circumscribes the fluidpassage openings and the electrochemical active portions of theassembly.

[0021] Another disclosure, WO 98/33225, is directed to a sealing thatpenetrates an edge of at least one gas diffusion electrode (GDE) wherebythe pores of the electrodes are filled. In that disclosure, the sealingis bonded to the membrane where the sealing penetrates the electrodesand comes into contact with the membrane and is also bonded to theperipheral face of the membrane. Both surfaces of the membrane areessentially completely covered by the electrodes.

[0022] The latter two concepts, which are based on impregnation of gasdiffusion electrodes (GDEs) with a sealant material, suffer from thecomplexity of the impregnation process. Even small deviations of theprocess parameters strongly affect quality of sealing and the smoothnessof the contact surface of the sealed area. Consequently, it is verydifficult to obtain gas-tight seals.

[0023] In light of the shortcomings of the prior art, the presentinvention is directed to an improved catalyst-coated membrane thatavoids the described disadvantages of the state of the art. Inparticular, the present invention provides a catalyst-coated membraneembracing one or more protective film layers that offers the followingadvantages: (i) improved mechanical stability; (ii) improved protectionagainst membrane damage; and (iii) improved handling properties incell/stack assembly. The present invention also provides an improvedmembrane-electrode-assembly (MEA) that offers the above-mentionedadvantages. Finally, a process for manufacture of these improvedproducts is outlined.

SUMMARY OF THE INVENTION

[0024] The present invention relates to the field of electrochemicalcells and fuel cells, more specifically to polymer-electrolyte-membranefuel cells (PEMFC) and direct methanol fuel cells (DMFC), and describescatalyst-coated ionomer membranes (“CCMs”) embracing one or more filmlayers for protection, sealing and handling purposes. Thecatalyst-coated membranes may, for example, be used as components formembrane-electrode-assemblies (MEAs) in low temperature fuel cellstacks.

[0025] According to one embodiment, the present invention provides acatalyst-coated membrane that comprises:

[0026] a) an ionomer membrane, wherein said ionomer membrane comprisestwo surfaces and each of said two surfaces is comprised of:

[0027] (i) an active area, wherein said active area is coated with acatalyst layer; and

[0028] (ii) a passive area; and

[0029] b) at least one layer of protective film attached to each of thetwo surfaces of said catalyst coated membrane, wherein said at least onelayer of protective film overlaps the active area and the passive area.

[0030] According to a second embodiment, the present invention providesa catalyst-coated membrane-electrode-assembly comprising:

[0031] (a) an ionomer membrane, wherein said ionomer membrane comprisestwo surfaces and each of said two surfaces is comprised of:

[0032] (i) an active area, wherein said active area is coated with acatalyst layer, and

[0033] (ii) a passive area; and

[0034] (b) at least one gas diffusion layer, wherein said at least onegas diffusion layer covers the active area of said catalyst-coatedmembrane; and

[0035] (c) at least one layer of protective film, wherein said at leastone layer of protective film contacts the active area, the passive areaand the gas diffusion layer to form:

[0036] (i) an overlapped region of the active area,

[0037] (ii) an overlapped region of the passive area, and

[0038] (iii) an overlapped region of the gas diffusion layer.

[0039] In both of these embodiments, the passive area is the area of theionomer membrane that has not been coated with a catalyst layer, andpreferably, it forms a perimeter around the active area.

[0040] These CCM and MEA are preferably manufactured under pressure andheat for a period of 0.1 to 15 minutes. More preferably, the pressure isin the range of 10 to 100 bar and the temperature is in the range of 20to 200° C.

BRIEF DESCRIPTION OF THE FIGURES

[0041]FIG. 1 is a representation of a catalyst-coated membrane (CCM)according to a first embodiment of the present invention.

[0042]FIG. 2 is a representation of a cross-section of a membraneelectrode assembly (MEA) with protective film layers according to asecond embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0043] The present invention is directed to catalyst-coated membranesand membrane-electrode-assemblies that contain ionomer membranes thathave both an active area, which has a catalyst layer, and a passivearea. Both of these areas are at least in part coated with a protectivefilm. In the MEA, the active area may be coated with a gas diffusionlayer.

[0044] The present disclosure is not intended to be a treatise oncatalyst-coated membranes or membrane-electrode-assemblies. Readers arereferred to appropriate available texts for background on thesesubjects.

[0045] According to the present invention, the catalyst coated membranepreferably comprises an ionomer membrane that itself is comprised of asubstance selected from the group consisting of perfluorinated sulfonicacid polymers, acid-doped polybenzimidazoles, acid-group-modifiedpolyetherketones, ionically conductive organic/inorganic materials andcomposite reinforced materials.

[0046] Ionomers membranes typically have two sides that containcatalytically active materials. Each of these sides is referred toherein as a “surface.” On each of the two surfaces of the ionomermembrane, there is both an active area and a passive area. The activearea, which corresponds to the electrode area is coated with a catalystlayer. The passive area, which is not coated, preferably forms aperipheral rim around the active area.

[0047] A protective film layer covers at least a portion of both theactive area and the passive area. The protective film layer embraces theCCM on both sides of the membrane, and has two main features. First, itoverlaps the active area in a certain region sufficient for preventionof membrane damage. Second, it overlaps a significant region of thepassive, non-coated area of the CCM. The region of the active areaoverlapped by the protective film layer is preferably in the range of0.5 to 20% of the total active area, and more preferably in the range offrom 3 to 10%. On the other hand, the region of the passive membranearea overlapped by the protective film layer is preferably in the rangeof 80 to 150%, more preferably in the range of 80 to 100% and mostpreferred equal to 100%, of the total non-coated membrane area.Overlapping of more than 100% in the context of the present inventionmeans that the protective film would extend over the periphery of theionomer membrane.

[0048] Preferably, the film comprises an organic polymer material with athickness in the range of 10 to 150 microns. More preferably, theorganic polymer material is a thermoplastic or duroplastic polymercomprised of a polymer selected from the group consisting ofpolytertrafluoroethylene, PVDF, polyester, polyamide, co-polyamide,polyamide elastomers, polyimide, polyurethane, polyurethane elastomers,silicones, silicon rubbers and silicon based elastomers.

[0049] Generally, one or more film layers can be applied on the frontand/or on the back surface of the catalyst-coated membrane. Duringlamination, the protective film softens and can penetrate the electrodelayer.

[0050] In a preferred embodiment, the protective film layers are appliedas frames on both sides of the ionomer membrane. However, other patternsand dimensions are possible.

[0051] The protective film layer or layers may be punched or perforatedas needed for certain bipolar plate and PEM stack architectures.Additional layers of protective films, such as gaskets or sealantmaterials may be added afterwards.

[0052] The present invention has two major embodiments, which aredemonstrated in FIGS. 1 and 2, and that may be incorporated into andoperated in fuel cells such as PEMFCs and DMFCs.

[0053]FIG. 1 shows a schematic drawing (cross section) of acatalyst-coated membrane (CCM) according to the first embodiment of thepresent invention. According to this embodiment, the ionomer membrane(1) is coated on both sides with an electrode layer (2) forming theactive area of the catalyst-coated membrane. Two frames of protectivefilm layer (3) are applied on both sides to the passive area of themembrane (1) in such a way that the film layers overlap with theelectrode layers in an area region (4), and, simultaneously, with thepassive, non-coated area of the ionomer membrane in an area region (5).On each side of the membrane, the region covered or overlapped by theprotective film layer is in the range of 0.5 to 20% of the total activearea of the membrane.

[0054] The protective film may be made of a polymer that is more rigidthan the ionomer membrane. The thickness of the protective film ispreferably in the range of 10 microns to 150 microns (more preferably inthe range of 80 to 120 microns), which enables it to constitute aprotection for the ionomer membrane against pressure, impact, wear,heat, drying out, etc. The protective film layer is tightly fixed ontothe membrane. It can be pre-shaped and heat-laminated or attached by anadhesive onto the membrane. It can also be formed by coating (by pasteapplication, printing process, etc.) the non-coated membrane area withan appropriate polymer paste or polymer emulsion.

[0055] The respective materials should be stable and resistant to theoperating conditions of a PEM fuel cell. Furthermore, the materialsshould have high endurance and lifetime, as well as high purity inrespect to trace contaminants, residual volatile components and otherinorganic or organic materials that could be leached out duringoperation of the fuel cell.

[0056]FIG. 2 depicts a cross-section of a membrane electrode assembly(MEA) with protective film layers according to the second embodiment ofthe present invention. In this second embodiment, the active area of theCCM according to embodiment 1 is covered by gas diffusion layers (GDLs)in such a way, that the gas diffusion layers contact, overlap and/orpenetrate the protective film layer applied to the CCM. Again, theionomer membrane (1) is coated with an electrode layer (2) on bothsides. The area of the active layer (2) (the “active area”) is smallerthan the total area of the ionomer membrane, which results in aperipheral rim of uncoated ionomer material (which is the passivenon-coated area) around the central active area of the CCM. As alreadydescribed in embodiment 1, two frames of protective film layers (3) areattached on both sides to the passive area of the membrane (1) in such away that the film layers overlap with the electrode layers in an arearegion (4), and, simultaneously, with the passive, non-coated area ofthe ionomer membrane in an area region (5). On each side of the CCM, theregion covered/overlapped by the protective film layer is in the rangeof 0.5 to 20% of the total active area. Both surfaces of the CCM areadditionally covered by gas diffusion layers (6). These two gasdiffusion layers (GDLs) overlap/contact the protective film layerdisposed over part of the active area at both sides of the membrane(overlapping region 7).

[0057] In a preferred embodiment, the dimensions of the GDL and that ofthe active area are identical. In this case, the region of the activearea of the CCM overlapped by the protective film and the region of theGDL in contact with the protective film are identical. However, otherembodiments, involving GDLs with bigger or smaller dimensions comparedto the active CCM area, are possible. Thus, the region of the GDLcontacted by the layer of protective film can be in the range of 0.5 to50% of the total area of the gas diffusion layer.

[0058] It is furthermore feasible, to provide the protective film in afirst step as a liquid, to press the GDL into the liquid film and tocure the film providing a solid protective film penetrating the GDL.

[0059] Commercially available GDLs, as well as other suitable materialscan be used for the formation of the membrane-electrode-assembly (MEA)according to this invention. As base materials for GDLs, woven carboncloth, non-woven carbon fiber layers or carbon fiber papers can be used.Typical GDL base materials include Toray TGP-H-060 and Textron AvCarb1071 HCB supplied by Textron Inc. The gas diffusion layers may or maynot be treated to be hydrophobic. Additionally, they may compriseadditional carbon black microlayers and catalyst layers, if necessary.

[0060] Bonding of the GDLs to the CCM can be conducted by application ofpressure and heat. Appropriate bonding or laminating conditions have tobe adopted to the mechanical stability of the individual base materialof the GDLs.

EXAMPLES

[0061] The following examples describe the scope of the invention inmore detail. These examples are presented to aid in an understanding ofthe present invention and are not intended, and should not be construed,to limit the invention in any way.

Example 1

[0062] The catalyst-coated membrane used in this example wasmanufactured according to U.S. Pat. No. 6,309,772, example 3, ink A. A40 wt. % Pt/Vulcan XC72 catalyst was used as cathode catalyst, and a 40wt. % PtRu (1:1)Vulcan XC72 was employed for the anode side. The CCMproduct is available at OMG under the designation “CCM-Type 7C” and wasused with a 100 cm² (10×10 cm) of active area. The passive area (thenon-coated area) of the CCM had a size of 1.0 cm in width, resulting inoverall CCM dimensions of 12×12 cm with the active area centered in themiddle.

[0063] Co-polyamide Vestamelt 3261 (Degussa, Düisseldorf) was providedas an extruded film of 120 μm thickness. From this film, twosquare-sized frames were punched with inner dimensions of 9.8×9.8 cm andouter dimensions of 12×12 cm.

[0064] The catalyst-coated membrane was placed between the two frames ofprotective film, and the assembly was covered by two sheets of PTFEblanks. The protective film frames were positioned with respect to thecatalyst-coated membrane so that the peripheral membrane rim wascompletely covered, and a 2 mm broad region of the active area wasoverlapping with the inner edge of the frame of protective film on bothsides of the CCM. Thus, the area of the overlapping region was 4% of thetotal active area on both sides of the CCM. The region of the protectivefilm overlapping with the non-coated membrane area was 100% of the totalnon-coated membrane area on both sides of the CCM.

[0065] The package was placed between two graphite press plates andtransferred into a press with a temperature of 165° C. Lamination wascompleted after 3 minutes at a pressure of 27 bar. The whole package wascooled down to room temperature while maintaining the pressure and thenreleased from the press and disassembled. The frame of protective filmsaround the active area adhered very well to both sides of the CCM.

[0066] Subsequently, the catalyst-coated membrane and two gas diffusionlayers (GDLs), one on the anode side and one on the cathode side, weremounted into a PEM single cell and tested in hydrogen/air operation at2.7 bar operating pressure at 70° C. cell temperature. The electricalperformance was in the range of 650 mV at a current density of 600mA/cm². During and after operation, no leakage of reactive gases wasobserved. Furthermore, the CCM with the protective film layerswithstands frequent assembly and disassembly processes without damage.

Example 2

[0067] A catalyst-coated membrane (CCM) with protective film layers onboth sides was prepared according to the procedure described inexample 1. Instead of the co-polyamide material, a polyurethane-basedfilm material (Walopur 4201AU, Epurex/Germany) with a thickness of 90 μmwas used as the protective film layer. Lamination parameters were 27 barand a temperature of 145° C. for 2 minutes. The overlapping area of theprotective film was about 5% of the total active area on both sides ofthe CCM. Furthermore, the overlapping area of the protective film withthe non-coated area was about 100% of the total non-coated area. Thecatalyst-coated membrane and two GDLs were again mounted into a PEMsingle cell and tested in hydrogen/air operation at 1.0 bar/70° C. foran extended period of 300 hours. An excellent long-term performance wasobtained. Microscopic inspection of the catalyst-coated membrane showedno indications for damage, either in the protective layers or at theinterface between protective layer and active area of the CCM.

Example 3

[0068] A catalyst-coated membrane (CCM) with protective films wasprepared as described in example 1. The overlapping area of theprotective films on both sides of the CCM was 9.25% of the total activearea. The overlapping area with the passive, non-coated membrane areawas 100%. Then the catalyst-coated membrane was placed between two GDLs(Sigracet 30BC from SGL Carbon, Germany) and the assembly was coveredwith two Teflon blanks. The GDLs were of the same size as the activearea of the CCM (i.e. 100 cm²). The positioning of the gas diffusionlayers was so that they completely covered the active area of the CCMand simultaneously overlapped with the protective film layer, which inturn overlapped with the active area of the CCM (see e.g., FIG. 2).Thus, the contacting/overlapping area of each GDL with the protectivefilm layer was 9.25% of the total GDL area.

[0069] The complete package was placed between two graphite press platesin a press with a temperature of 170° C. Lamination was completed after3 minutes at a pressure of 25 bar. The whole package was cooled down toroom temperature while maintaining the pressure and then released fromthe press and disassembled. The GDLs adhered well to the CCM thusforming a 5-layer membrane electrode assembly (MEA) with protective filmlayers on both sides.

[0070] The MEA was mounted into a PEMFC single cell and tested inhydrogen/air operation at 1.0 bar/70° C. for 300 hours. A good long-termperformance was obtained. Microscopic inspection of the 5-layer MEAshowed no indications for damage, either in the protective layers or atthe interface between the protective layers and the active area of theMembrane Electrode Assembly.

[0071] Having thus described and exemplified the invention with acertain degree of particularity, it should be appreciated that theclaims that follow are not to be so limited but are to be afforded ascope commensurate with the wording of each element of the claims andequivalents thereof.

1. A catalyst-coated membrane comprised of: (a) an ionomer membrane,wherein said ionomer membrane comprises two surfaces and each of saidtwo surfaces is comprised of: (i) an active area, wherein said activearea is coated with a catalyst layer, and (ii) a passive area; and (b)at least one layer of protective film attached to each of the twosurfaces of said catalyst-coated membrane, wherein said at least onelayer of protective film overlaps the passive area and the active area.2. The catalyst-coated membrane according to claim 1, wherein saidpassive area forms a perimeter around said active area.
 3. Thecatalyst-coated membrane according to claim 1, wherein the region of theactive area that is overlapped by the at least one layer of protectivefilm is in the range of 0.5 to 20% of the total active area of themembrane, and the region of the passive area that is overlapped by theat least one layer of protective film is in the range of 80 to 150% ofthe total passive area.
 4. The catalyst-coated membrane according toclaim 1, wherein the at least one layer of protective film comprises anorganic polymer material with a thickness in the range of 10 to 150microns.
 5. The catalyst-coated membrane according to claim 4, whereinthe organic polymer material comprises a polymer selected from the groupconsisting of polytetrafluoroethylene, PVDF, polyethylene,polypropylene, polyester, polyamide, co-polyamide, polyamide elastomers,polyimide, polyurethane, polyurethane elastomers, silicones, siliconrubbers, and silicon based elastomers.
 6. The catalyst-coated membraneaccording to claim 1, wherein the ionomer membrane comprises a substanceselected from the group consisting of perfluorinated sulfonic acidpolymers, acid-doped polybenzimidazoles, acid-group-modifiedpolyetherketones, ionically conductive organic/inorganic materials andcomposite reinforced materials.
 7. A process for manufacturing acatalyst-coated membrane, said process comprising applying at least onelayer of protective film to two surfaces of an ionomer membrane underpressure and heat for a period of 0.1 to 15 minutes, wherein said twosurfaces each comprise a passive area and an active area, wherein saidactive area is coated with a catalyst layer.
 8. A process formanufacturing a catalyst-coated membrane according to claim 7, whereinthe pressure is in the range of 10 to 100 bar and the heat establishes atemperature in the range of 20 to 200° C.
 9. Amembrane-electrode-assembly comprised of: (a) an ionomer membrane,wherein said ionomer membrane comprises two surfaces and each of saidtwo surfaces is comprised of: (i) an active area, wherein said activearea is coated with a catalyst layer, and (ii) a passive area; and (b)at least one gas diffusion layer, wherein said at least one gasdiffusion layer covers the active area of said catalyst-coated membrane;and (c) at least one layer of protective film, wherein said at least onelayer of protective film contacts the active area, the passive area andthe gas diffusion layer to form: (i) an overlapped region of the activearea, (ii) an overlapped region of the passive area, and (iii) anoverlapped region of the gas diffusion layer.
 10. Themembrane-electrode-assembly according to claim 9, wherein the region ofthe active area contacted by the at least one layer of protective filmis in the range of 0.5 to 20% of the total active area of the membrane,the region of the passive area contacted by the at least one layer ofprotective film is in the range of 80 to 150% of the total passive areaof the membrane and the region of the gas diffusion layer contacted bythe at least one layer of protective film is in the range of 0.5 to 50%of the total area of the gas diffuision layer.
 11. A process formanufacturing a membrane-electrode-assembly, said process comprisingapplying a gas diffusion and at least one protective film to twosurfaces of an ionomer membrane under pressure and heat for a period of0.1 to 15 minutes, wherein said two surfaces each comprise a passivearea and an active area, wherein said active area is coated with acatalyst layer.
 12. A process for manufacturing amembrane-electrode-assembly according to claim 11, wherein the pressureis in the range of 10 to 100 bar and the heat establishes a temperaturein the range of 20 to 200° C.
 13. A method of using the catalyst-coatedmembrane of claim 1, comprising operating a PEM or DMFC fuel cell stackthat comprises the catalyst-coated membranes of claim
 1. 14. A method ofusing the membrane-electrode-assembly of claim 9, comprising operating aPEM or DMFC fuel cell stack that comprises themembrane-electrode-assembly of claim 9.